sync-v2 step 1: worker roles + interactive/bulk queue split

- config: WORKER_ROLE (sync|jobs|all), INTERACTIVE_CONCURRENCY, BULK_CONCURRENCY.
- queue: named queues (interactive/bulk) + enqueue_job() router; sync_bootstrap
  goes to bulk, all other jobs to interactive.
- workers.run: single entrypoint; role=jobs runs both arq consumers (per-queue
  timeout/concurrency), role=sync runs the supervisor, all=both (dev default).
- docker-compose: worker-sync + worker-jobs services (shared image, nofile
  ulimit); backend/Dockerfile; Makefile worker/worker-sync/worker-jobs targets.
- tests repointed to app.queue.get_arq_pool; supervisor behavior unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/migrations/versions/0006_user_quota.py

@@ -21,9 +21,7 @@ depends_on: str | Sequence[str] | None = None
 
 
 def upgrade() -> None:
-    op.execute(
-        "ALTER TABLE users ADD COLUMN quota_bytes bigint NOT NULL DEFAULT 5368709120"
-    )
+    op.execute("ALTER TABLE users ADD COLUMN quota_bytes bigint NOT NULL DEFAULT 5368709120")
 
 
 def downgrade() -> None: